Inverting Megathrust Paleoseismic Records to Improve our kNowledge of Temporal and Spatial rupture variability

Objective

Constraining the spatiotemporal variability of megathrust earthquakes is one of the key challenges in subduction zone research around the world. Such understanding is critical for reliable seismic hazard assessments, requiring knowledge of size, location and timing of past earthquakes to estimate future risks. A key discipline providing the necessary continuity and sensitivity to accurately record past earthquakes is subaquatic paleoseismology, relying on the identification of shaking imprints in lakes, fjords and oceans. Unfortunately, a quantitative link between an earthquake’s sedimentary imprint and its source parameters (e.g., magnitude, location) is missing, meaning that the full potential of the methodology is still not achieved and critical information on megathrust earthquake dynamics remains obscured. The IMPRINTS project provides innovative advances to the state-of-the-art of subaquatic paleoseismology by combining it with physics-based ground motion modelling. This will be achieved by using sedimentological methods to reveal individual paleo-earthquakes, and propagating dislocation models for each of these events into ground motion models after validating them against coastal records of earthquake deformation. In this way, it combines the disciplines of sedimentology and seismology and enriches them with computational approaches, allowing for the first quantitative evaluations of the spatial and temporal variability of megathrust ruptures. These unprecedented insights into subduction zone earthquake dynamics will subsequently be used to test and validate national seismic hazard models, which will ultimately benefit society through improved seismic and tsunami hazard maps. IMPRINTS thus creates a significant impact that reaches beyond academia and contributes to the overall aim of earthquake risk mitigation.